For many types of marine refrigeration setups, the pressure of the refrigerant flowing through the system is an important data point. For example, a steady loss of pressure in the system over time would tend to indicate a leak. That's something you'd like to know without having to bring in a service technician. Would be great if you could pull up an app on your smartphone and check your refrigerant pressure just to make sure that your beer is staying cold (along with all the other foodstuffs you've stored in your frig box). Now there is a wireless Bluetooth transducer called the CirrusSense TDWLB from Transducers Direct that can sense refrigerant pressure and send the data to your iPhone or iPad or computer. Using an app called "T-Direct TDWLB", user can name each sensor, then program setpoints/alarms for multiple sensors, monitor readings, and graph activity over time.
From the press release: "Boat owners and marine service techs have told us this will save time and money by preventing equipment damage, fish/food spoilage, unneeded service calls, downtime, and premature refills," said Rob Matthes, President of Transducers Direct. "The pressure of any fluid can be monitored from vacuum to 10,000 psi. Boat owners or marina operators can read refrigerant pressures remotely, any time, without a service tech and the clumsy manifold gauges. The sensor also ends refrigerant leaks and blowback from manifold gauges, so it's EPA friendly. There's no gauge recalibration or adjustment. There has never been anything like this, and we'll be announcing expanded capabilities for this platform in coming months."